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Central Heating


d3fy
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All,

I know we have at least one Plumber on the boards so I thought I would post.

Had some problems with the central heating having just moved in, first there was dead spots all over the rads so I took them off and blasted them through with the hose pipe. What could be described as pure black sh*t poured out. So back on and all's well, for a few days then the there was some really loud rattling and banging on the pipes around the pump, I then noticed a day are so later that it was ****** water into the kitchen below the pump had sprung a leak, so replaced the pump and alls well except...... I now have brown hot water, and I know that the hot water runs of a different system to the central heating?

Sooooo, any ideas :crybaby:

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The rattling and banging was most probably air in the pump - but where from? That is what probably did the pump seals.

Is your system a combi system or do you have a hot water cylinder?

If you have a cylinder (with an immersion backup)

The brown hot water could be two things 1:- the coil in the hot water cylinder has sprung a leak - unlikely but possible or 2:- the plumber has has cocked up and put the vent pipe into the hot water header tank and not the central heating header tank - that is if he bothered fitting a header tank and your new pump is probably set too high.

They are my idea's - hope it helps.

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Assuming it's Combi, is it the type with a built in filling loop?

Make sure the valve is completely closed, or it's possible the valve itself between the primary circuit and the DHW may be faulty.

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Thanks all - great group of people we have on here! Really thanks, but sodds law. I have put up with it for 4 days and then hours after I post the missus calls to say its running clear at last !!!!

I think the old pump packed up the banging was due to the air not getting through the dead pump, the new pump was set too high and was creating air, this had me scratching my head for days trying to figure out why I had to bleed the rads every few hours - but I have no idea what caused the brown hot water, its not a combi, I do have a cylinder and it should be all plumbed in alright as all I changed was the pump.

The guy at Wickes asked if I had been mixing cement with the old pump as it was covered in solid black crud.

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If you have the pump set too high it pumps up out into the header tank. This causes aeration in the header tank and because you are pumping out it sucks this aeration back in. But that shouldn't cause your hot water to be discoloured - unless the vent is into the wrong tank!

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Its still no 100%, I did run off all the hot water and had all the hot taps open, so I just figured I had dragged some crap into the system? Its better now, but still not great do you think it will just settle and disapear?

PS.

Glynn if your a plumber and you drive a RX then you have just confirmed for me that I'm in the wrong business :winky:

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If you have the pump set too high it pumps up out into the header tank. This causes aeration in the header tank and because you are pumping out it sucks this aeration back in. But that shouldn't cause your hot water to be discoloured - unless the vent is into the wrong tank!

If there's a lot of sediment in the bottom of the header tank then this may get sucked back in and discolour the water?

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Not a plumber and never have been. I'm an early retired factory engineer. Retired by a new younger boss who thought he knew more than me.

Rodders :- yes but the discolouration was in the domestic taps not the radiators so there must be a cross over in the systems somewhere and the only time it appeared was after a new pump had been fitted - and run too fast, so I still think the heating is vented into the domestic system or there is some cross over in the header tank area - maybe a common overflow?

Good this in'it?

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Anyone thimnking of getting British gas boiler cover should try direct line who offer the best cover for central heating and boiler they dont come out to inspect prior to accepting you for insurance like B/gas do, then if your problem persists call them out.

By the way anyone thinking i work for direct line i don't ,Heating engineers i've worked with have all recommended them.

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Anyone thimnking of getting British gas boiler cover should try direct line who offer the best cover for central heating and boiler they dont come out to inspect prior to accepting you for insurance like B/gas do, then if your problem persists call them out.

By the way anyone thinking i work for direct line i don't ,Heating engineers i've worked with have all recommended them.

:shifty:

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If you have emptied the hot water header tank by running all the hot water off then Rodders reply might be correct - but why would you do that if the initial problem was with the central heating and not the hot water?

The central heating header tank is usually a lot smaller than the hot water header tank and this smaller tank should have a vent pipe from the central heating system coming back into the top of the tank but stopping short of the water level.

The hot water header tank should also have a vent pipe coming back into the top of the tank from the hot water cylinder.

Older houses could also have a cold water header tank usually the same size as the hot water header tank but this will not have a vent pipe.

If you are still having problems let the central heating system warm up and feel the header tanks. They should be cold. If they are warm you are still getting recirculation.

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<snip/>

If you have emptied the hot water header tank by running all the hot water off then Rodders reply might be correct - but why would you do that if the initial problem was with the central heating and not the hot water?

Cause I'm not very clued up on heating and vent but I'm learning when it started knocking I panicked and drained the hot water from the tank thinking that would reduce the pressure?

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